Submersible catamaran for the placement and withdrawal of packages ona water bottom

ABSTRACT

A submersible vehicle of the catamaran type which is used to raise and lower load to and from the bottom of a body of water. The vehicle comprises two ballasts tank held together by beams and a platform position on the beams. The platform has an open center area through which the loads are attached to or separated from the vehicles. The vehicle is raised or lowered by forcing air into or expelling air from the ballasts tank.

United States Patent [111 3,713,411 Bordessoule et al. [4 1 Jan. 30, 1973 [54] SUBMERSIBLE CATAMARAN FOR THE PLACEMENT AND WITHDRAWAL [56] References Cited OF PACKAGES ON A WATER BOTTOM UNITED STATES PATENTS [75] Inventors: Rene F. Bordessoule, 78 Carrieres 3,589,133 6/l97l Lowd ..ll4/l6RX Sur Seme; Kermabm 3,495,562 2/1970 Fahlman etal. ..ll4/l6R Marsene 9e; Serge De Vera 95 2,887,977 5 1959 Piry ..H4/l6E Garces les Gonesse, all of France [73] Assignees: Compagnie Francaise des Petroles, Primary y 311) Paris; Comex-Equipment, Marseille, ttorneySughrue, Rothwell, Mion, Zinn & Macpeak France [22] Filed: Feb. 10, 1971 [57] ABSTRACT A submersible vehicle of the catamaran type which is [21] Appl 113047 used to raise and lower load to and from the bottom of a body of water. The vehicle comprises two ballasts [30] Foreign Application Priority Data tank held together by beams and a platform position on the beams. The platform has an open center area Feb. ll, 1970 France ..70()4774 through which the loads are attached to or Separated from the vehicles. The vehicle is raised or lowered by forcing air into or expelling air from the ballasts tank.

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AAA/URAW L INVENTORS RENE F. BORDESSOULE ANDRE J. KERMABON SERGE DEVERA BY vakrwu $5M M,

73 A WK ATTORNEYS PATENTEDJAH 30 I975 SHEET 3 OF 3 SUBMERSIBLE CATAMARAN FOR THE PLACEMENT AND WITHDRAWAL OF PACKAGES ON A WATER BOTTOM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a submersible vehicle of the catamaran type for placing and withdrawing heavy or light packages upon and from a lake or ocean bottom, as well as to the method of accomplishing same.

2. Description of the Prior Art The development of the exploration of ocean bottoms and especially the exploitation of submarine petroleum wells has necessitated the placement, on a marine bottom and the return to the surface, of cargo in well-defined places. For this purpose, one may immobilize, on the surface, a ship equipped with hoisting means. However, experience has shown that it is always difficult, especially in the presence of wind, to keep the ship precisely perpendicular above the place where the package or cargo must be deposited or picked up.

SUMMARY OF THE INVENTION It is the object of this invention to provide a raft of the catamaran type, capable of supporting heavy loads and characterized by the fact that it involves two ballasts tanks which are connected together by beams. An empty space between the ballast tanks and the beams is for the placement of the package to be transported. Tying means are provided for securing said packages. At least on lattice platform is positioned between the two ballast tanks. The raft also includes compressed-air tanks, at least one air escape valve and one compressed-air inlet valve which are connected to a duct which is connected between the upper portion of each of the ballast tanks. An individual water introduction and evacuation valve is provided for each ballast tank, and means are provided for the manual control of each air inlet and outlet valve associated with pressure gauges that measure the hydrostatic pressure and the pressure prevailing in the ballast tanks, as well as an assembly of manual control means for each valve.

This raft has many advantages over prior art devices. Packages weighing several tons, for example, may be loaded with the help of port facilities in the space on the raft which is to be situated above or below the wells. The raft is then towed in the horizontal direction to the place where the package is to be deposited. Towing is accomplished under good stability conditions because of the lowering of the center of gravity obtained by the placement of the package which is in the water in the center of the raft. Once it has arrived in a line vertical from the place where the cargo is to be deposited, it is only necessary to operate the air escape and inlet or the water evacuation pipes in order to lower the raft along the vertical line which, except in the presence of a submarine current, will experience very little horizontal displacement due to the central opening provided in the raft. In the prior art when a ship is immobilized for the purpose of vertically lowering or raising a package by cable, moved by a crane, it is generally difficult to obtain only small horizontal displacements. When the raft reaches the bottom and deposits the package, the vehicle can rise up along a vertical path from the place of work by simply evacuating the water from the ballast tanks by means of compressed-air. Moreover, the horizontal displacement of heavy loads on the bottom becomes easy since it suffices to give the vehicle zero or very little buoyancy. In this way a very economical, simple, and efficient apparatus is obtained which is capable of transporting several tons, either from the surface to the bottom of the water or vice verse, or from one point to another on the bottom, with very great movement precision.

Another object of the invention is a raft of the type indicated which includes a skid under each ballast tank and a float above and parallel to each ballast tank.

The chief advantage of this arrangement is that it improves the stability qualities of the vehicle, by lowering the center of gravity due to the presence of the skids and by raising the center of thrust due to the presence of the floats. From the increase in stability, even in case of false maneuvers, which may occur in the course of the placement on the water bottom or when the vehicle is placed on a bottom that is not horizontal, the vehicle cannot tip over. Moreover, in addition to the contribution of the skids to the stability of the vehicle, they also permit recovery of the vehicles thus equipped and permit placing them on a pier or a ship so that the tanks are protected against damage.

Another object of the invention is an apparatus of the type indicated, where we divide each ballast tank into three compartments, the two end compartments in each ballast tank having a common air escape duct connected with the common duct of the two extreme compartments of the other ballast tank, while the central compartments of each ballast tank have a common air escape duct different from the preceding duct and each of the six compartments thus formed has a manual control valve for the inlet and outlet of water arranged on a control footbridge.

Such an arrangement facilitates the operation of placement on the bottom and disengagement in case the device should sink into the bottom nonuniformly since the extreme compartments can be made heavier or lighter individually so as to facilitate the possible disengagement of the skids, while the central ballast tanks can be made lighter rapidly and simultaneously by the simple operation of the common compressed-air introduction control after the opening of the correspondin g water evacuation valves.

Other advantages and features of the invention will emerge from the following specifications with reference to the attached drawing which, by way of nonrestrictive example, represents one way of executing a submersible raft with central holes facilitating the discharge of cargo transported.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan and top view of the vehicle;

FIG. 2 is a lateral and longitudinal view; and

FIG. 3 is an end view taken from the side of the control bridge.

DESCRIPTION OF THE PREFERRED EMBODIMENT The plan view of FIG. 1 illustrates a submersible raft capable of putting in place, with great precision, or

raising with full safety, packages weighing on the order of 5 tons. The raft is capable of reaching depths on the order of 50 meters.

Ballasts tanks 1, whose length in the embodiment shown is on the order of 5 meters, are positioned in their upper portion, through an assembly of transversal beams 2 and longitudinal beams 3, giving the assembly the necessary rigidity and permitting the tying of cargo to be displaced. The tie-up rings provided for this effect have been shown at 4.

A general planking made up of a permeable grating 5, is placed on the assembly of the raft beyond the recess 6 reserved for the typing of the cargo weighing several tons. In addition to rings 4, we can arrange a central beam for the purpose of tying the package. However, the stability provided by floats 28 is such that it is also possible to arrange the loads on the planking if loading conditions so require.

A keel 7, which may be made of an l-shaped steel beam, is shown in FIGS. 2 and 3, longitudinal and below each ballast tank. 7

Each ballast tank 1, in FIGS. 1 and 2, is divided into three compartments labeled, in the drawing, A, X, B for one of them, and C, Y, D for the other one. The compartments A, B, C and D, which have a large volume, give the assembly a buoyancy that will be almost zero by simply regulating the volume of water introduced. These compartments are designed to resist the outside ambient pressure at a depth on the other of 50 meters, according to known techniques. In particular, in order to increase the stability of the assembly, each of these four compartments is itself divided by partitions l2 and 13 for A, and 14 and 15 for B into three elements such as A A A and B B and B as shown in FIG. 2. The elements of each compartment are connected among each other through siphons 8 and 9 for compartment A, and 10 and 11 for compartment B.

The central compartments X and Y have a smaller capacity and assure the immersion and emersion movements at a slow rising speed, on the order of l m/sec. This is obtained through ballasting regulated by means of manual controls placed on the footbridge joining the compartments A and D in FIG. 1.

These controls include handles MA, MB, MC and MD for the control of valves VA, VB, VC and VD which provide for the connection between the lower part of each compartment and the ambient medium. The valves are used for introducing or evacuating water. Likewise, handles MX and MY assure the opening and closing of valves VX and VY which control the introduction or evacuation of water outside the central compartments. Several of these valves such as 16-19 1 are arranged to enable the complete emptying of the partition elements of each compartment. These valves are arranged in recesses in keels 7 which are provided for this purpose.

Compressed-air tanks 20, arranged below the catwalk, are used to pressurize the water stored in each compartment and in each ballast tank. For this purpose, these tanks are connected to conduit 21, feeding the ducts 22 and 23, controlled, respectively, by valves V and V The duct 22 connects the upper portions of the ballast tank A, B, C and D to the valve V the duct 23 connects the upper portion of ballasts X and Y to the valve V It then sufiices to operate the valve V in order to pressurize the assembly of ballast tanks A, B, C. and D and to operate V in order to pressurize X and Y.

The valves V and V arranged, respectively, at the end of ducts 22 and 23 provide a connection between each of the ducts and the surrounding medium, thus allowing pressurized air to escape.

The pressure gauges 24, 25, 26 and 27 control, respectively, the air pressure available and compressed to 200 bars, the pressure of tanks A, B, C and D, the pressure in tanks X, Y and the hydrostatic pressure.

In addition to the ballast tanks, two floats 28 increase the stability of the raft by shifting the dynamic center upward. These floats are mounted for this purpose above the ballast tanks and they are spaced at the maximum distance from each other without increasing the width of the raft. The distance is limited by ballast tanks A, B, C and D.

The raft further includes (not shown) tie-up rings for towing the raft, access ladders, hoisting rings, etc. Ringcarrying columns 29 are distributed around the planking and are capable of serving as tie-up points.

The floats and the ballast tanks are preferably made of soft, electrically welded steel. The bottoms are stamped and have manholes for access to the interior. Circular outside grooves are welded on ballast tanks in order to enable them to resist an outside pressure in 50 meters of water; here, rounded-off protecting pieces 30 and 31 prevent direct impacts upon the ballast tanks. Supplementary air escape valves, such as 32, facilitate the regulation of the trimming or emptying of the extreme ballast tanks.

The apparatus is operated under the following conditions.

To lower a load, the assembly is given a slightly positive buoyancy. For this purpose, a certain volume of water is progressively introduced into the ballast tanks A, B, C and D, opening the water inlet valves VA, VB, VC and VD, as well as the air escape vale V The trim of the vehicle is regulated by closing one or more of these valves to attain a slightly positive buoyancy on the order of 200 kg, for example, and then closing the four water inlet valves VA, VB, VC and VD, as well as the air escape valve V The buoyancy is then adjusted to obtain a slow descending speed on the order of meters per minute, using ballast tanks X and Y. To do this valves VX and VY are opened for the purpose of letting water into the ballast tanks along with the opening of the corresponding air escape valve V The vehicle then becomes heavy and begins to descend. The valves V VX and VY are then closed. If an operator estimates that the speed of descent is too slow, he can open the water inlet valves VX and VY until he gets the weight that gives him the desired speed. When the desired speed has been reached, the diver closes the valves VX and VY.

Furthermore, the inside pressure in the ballast tanks is increased until it is greater than the hydrostatic pressure. The operator then opens the compressed-air inlet valve V until the pressure read off on the pressure gauge 26 is greater than that on the pressure gauge 27, giving the value of the hydrostatic pressure. He then again closes the valve 12.

When the raft reaches the proximity of the bottom, all the operator has to do is simply to open the water escape valves VX and VY of ballast tanks X and Y in order to lighten the assembly and reduce its speed of descent. The operator then again closes the water escape valves VX and VY in order to prevent a return to positive buoyancy.

When the load transported touches the bottom, the vehicle resumes positive buoyancy. In order to permit the load to be-untied in complete safety, the operator adjusts the water inlet valves VA, VB, VC and VD, as well as the corresponding air escape valves V until the tension of the cargo tie-up slings diminishes. The operator can then reclose valves VA-VD as well as valve V Now that the vehicle has taken on a slightly positive apparent weight, it is possible to cast off the slings and to proceed to the operations involved in bringing the vehicle back up again.

After having made sure that the pressure in ballast tanks X and Y is the same as the hydrostatic pressure, the operator opens the water evacuation valves VX and VY and slightly opens the compressed-air inlet valve V The buoyancy now becomes positive, the vehicle begins to rise up again, and the operator can again close the escape valves VX and VY and the compressed-air inlet valve V The operator begins the operation over again or the opposite operaTion so as to attain a suitable raising speed.

After the vehicle has arrived on the surface, it is necessary to open the water evacuation valves VA, VB, VC, VD, VX and VY as well as the air escape valves V and V in order to give the vehicle sufficient buoyancy to facilitate towing. If a too strong current involves the risk of interfering with the descent or the raising, a guided cable can be used which has first been anchored at the desired place on the bottom. When the vehicle must recover a cargo from the bottom, a guided cable is passed into the holes of the vehicle and this cable is connected between the cargo to be recovered and a buoy on the surface. The buoy may have a thrust of 200 kg in order to produce a strong tension on the guide cable.

Then, as before, a slight positive buoyancy is obtained by letting water into the ballast tanks A, B, C and D and then getting slightly negative buoyancy by letting water into the ballast tanks X and Y.

in order to tackle the load as best as possible, it is best to reduce the speed as much as possible and to haul by hand with the help of the cable. When the vehicle is on the cargo, the water is ejected from ballast tank A, B, C and D in order to reduce the apparent weight of the assembly down to a zero value, and then to regulate the hoisting speed by ballast tanks X and Y.

Once on the surface, the water escape and compressed-air inlet valves are opened to give the assembly the necessary buoyancy for towing.

in this way a new means is obtained capable of lowering heavy loads on the order of several tons in the vertical direction from a given place and, inversely, capable of raising a load resting on the ocean bottom in order to bring it to the surface in the vertical direction from the given place. The assembly requires neither a craneequipped surface vessel nor the use of expensive submarines which must necessarily be provided with hoisting and locating means. Furthermore, no known submarine has a hole for handling cargo according to the method and apparatus described herein.

It is clear that many additions and modifications could be made in the details of the raft described without going beyond the framework of this invention. In particular, keels could be mounted to strengthen the navigation properties of the catamaran and an auxiliary motor could be provided in order to give it its own independent operation both on the surface and submerged. As for the equipment designed to facilitate the operations of the operators or to provide for their total safety, such equipment may be of any kind and may, in particular, involve devices that limit the speed with which the raft will rise again to the surface in case the operator should be in trouble.

While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

We claim:

1. A submersible raft for raising and lowering loads in water comprising,

a. a plurality of ballast tanks;

b. a plurality of beams coupled to said ballast tanks such that an open area is formed between said ballast tanks and said beams, wherein said load is positioned in said open area;

c. tie-up means connected to said raft for tying said load to said raft;

d. at least one lattice platform between said ballast tanks;

e. at least one compressed air tank;

f. air duct means connected between said ballast tanks;

g. compressed air inlet valve means connected between said air tank and said air duct means;

h. air escape valve means coupled to said ballast tanks;

. water valve means for permitting introduction and evacuation of water from said ballast tanks;

j. pressure measuring means for measuring the hydrostatic pressure and the pressure in said ballast tanks; and

k. control means for controlling the raising and lowering operation of said raft, said control means comprising at least one internal compartment in each of said ballast tanks, each said compartment having a smaller volume than its corresponding ballast tank and one control member corresponding to each of said compartments, for controlling said air inlet valve means, said air escape valve means, and said water valve means whereby raising and lowering of said raft is controlled by the operation of said control members.

2. The raft of claim 1 further including,

a. a skid connected to the bottom of said ballast tanks; and

b. float means coupled to said ballast tanks, above and parallel thereto.

3. The raft of claim 2,

a. wherein each ballast tank includes at least three internal compartments; and

b. wherein said air duct means comprises a,

1. first ballast air ducts connected between the two end compartments of each ballast tank;

2. a first common air duct connected to each of said first ballast air ducts;

3. second ballast air ducts connected to the central compartments of each ballast tank; and

4. a second common air duct connected to each of said second ballast tank air ducts.

4. The raft of claim 3 wherein the volume of said central compartment is between 5 and 30 percent of the volume of said end compartments.

5. The raft of claim 3 wherein said platform includes a control station and wherein said control members are positioned at said control station.

6. The raft of claim 5 wherein,

a. said air inlet valve means are connected to said first and second common air ducts; and 

1. first ballast air ducts connected between the two end compartments of each ballast tank;
 1. A submersible raft for raising and lowering loads in water comprising, a. a plurality of ballast tanks; b. a plurality of beams coupled to said ballast tanks such that an open area is formed between said ballast tanks and said beams, wherein said load is positioned in said open area; c. tie-up means connected to said raft for tying said load to said raft; d. at least one lattice platform between said ballast tanks; e. at least one compressed air tank; f. air duct means connected between said ballast tanks; g. compressed air inlet valve means connected between said air tank and said air duct means; h. air escape valve means coupled to said ballast tanks; i. water valve means for permitting introduction and evacuation of water from said ballast tanks; j. pressure measuring means for measuring the hydrostatic pressure and the pressure in said ballast tanks; and k. control means for controlling the raising and lowering operation of said raft, said control means comprising at least one internal compartment in each of said ballast tanks, each said compartment having a smaller volume than its corresponding ballast tank and one control member corresponding to each of said compartments, for controlling said air inlet valve means, said air escapE valve means, and said water valve means whereby raising and lowering of said raft is controlled by the operation of said control members.
 1. A submersible raft for raising and lowering loads in water comprising, a. a plurality of ballast tanks; b. a plurality of beams coupled to said ballast tanks such that an open area is formed between said ballast tanks and said beams, wherein said load is positioned in said open area; c. tie-up means connected to said raft for tying said load to said raft; d. at least one lattice platform between said ballast tanks; e. at least one compressed air tank; f. air duct means connected between said ballast tanks; g. compressed air inlet valve means connected between said air tank and said air duct means; h. air escape valve means coupled to said ballast tanks; i. water valve means for permitting introduction and evacuation of water from said ballast tanks; j. pressure measuring means for measuring the hydrostatic pressure and the pressure in said ballast tanks; and k. control means for controlling the raising and lowering operation of said raft, said control means comprising at least one internal compartment in each of said ballast tanks, each said compartment having a smaller volume than its corresponding ballast tank and one control member corresponding to each of said compartments, for controlling said air inlet valve means, said air escapE valve means, and said water valve means whereby raising and lowering of said raft is controlled by the operation of said control members.
 2. a first common air duct connected to each of said first ballast air ducts;
 2. The raft of claim 1 further including, a. a skid connected to the bottom of said ballast tanks; and b. float means coupled to said ballast tanks, above and parallel thereto.
 3. The raft of claim 2, a. wherein each ballast tank includes at least three internal compartments; and b. wherein said air duct means comprises a,
 3. second ballast air ducts connected to the central compartments of each ballast tank; and
 4. The raft of claim 3 wherein the volume of said central compartment is between 5 and 30 percent of the volume of said end compartments.
 4. a second common air duct connected to each of said second ballast tank air ducts.
 5. The raft of claim 3 wherein said platform includes a control station and wherein said control members are positioned at said control station.
 6. The raft of claim 5 wherein, a. said air inlet valve means are connected to said first and second common air ducts; and b. said air escape valve means are connected to said first and second common ducts.
 7. The raft of claim 4 wherein each end compartment of said ballast tanks comprises three elements, said compartments being divided into said elements by partitions such that the volume of each element is equal to a maximum of twice the volume of the central compartment, each end compartment further including siphons connected between contiguous elements. 